PRINCIPAL COMPONENT ANALYSIS OF BODY MEASUREMENTS IN A POPULATION OF INDIGENOUS NIGERIAN CHICKENS RAISED UNDER EXTENSIVE MANAGEMENT SYSTEM

This study was carried out to investigate the relationship among body measurements in indigenous Nigerian chickens sampled in Niger state using principal component analysis with the view of identifying components that best define body conformation in them. A total of 750 birds were used for the study. The parameters recorded were: body weight, body length, body girth, wing length, shank length and shank thickness. The descriptive statistics showed that the mean body weight was 1.69 kg while the body measurements were 38.77 cm, 25.30 cm, 22.23 cm, 11.01 cm and 1.10 mm for body length, body girth, wing length, shank length and shank thickness, respectively. The coefficients of correlation obtained were: r = 0.709 (between body weight and body length), r = 0.448 (between body weight and body girth), r = 0.667 (between body weight and wing length), r = 0.203 (between body weight and shank length) and, r = 0.499 (between body weight and shank thickness) respectively. Principal component analysis with variance maximizing orthogonal rotation was used to extract the components. Two principal components were extracted in the chickens explaining 66.4 % of the total variation in the original variables. Generally, the first principal component had the largest share of the total variance and correlated highly with body weight, body length and wing length while the second principal component had its loadings on shank length. These components could be used as selection criteria for improving body weight of indigenous Nigerian chickens.